The present invention relates to an one-body horizontal continuous casting apparatus and the methods of deoxidation and refining for fabricating a slab, rod or tube shape materials directly from the molten phosphorized copper by means of using a horizontal continuous casting process. In order to incorporate the technology of the horizontal casting apparatus with multiple steps, the process of deoxidation and refining to the one-body melting and casting machine with a unitary melting furnace and casting machine, and to reduce the cost associated with the apparatus construction, the present invention contemplates designing and manufacturing an one-body melting and casting machine, wherein molten metal is deoxidized and refined in the one-body melting and casting machine which comprises multi-staged graphite filters and a system with a rapid cooling capability.
Methods of continuous casting of a vertical, horizontal, or upward type have been employed until presently for production of high purity phosphorized copper for the purpose of plating, and the vacuum melting and casting method is used only for productions in small scale.
Of these methods for continuous casting, the vertical continuous casting process cannot provide a direct continuous casting of a small section in a near-net-shape. Thus, those of a large section have to undergo a vertical continuous casting in the first stage, after which, it is processed to form a slab, rod, or tube shape. Also, the upward continuous casting process cannot control the shape and the area of a section whereas the horizontal continuous casting process enables a direct continuous casting of the desired shape of a slab, rod, or tube.
Furthermore, the horizontal continuous casting process offers the advantage of continuous casting of highly purified molten metal without the fear of oxidation by receiving the molten metal directly from the lower part of the casting furnace. Thus, such process is suitable for producing phosphorized copper.
Despite of all these advantages, an one-body horizontal continuous casting apparatus for phosphorized copper and the production method thereof using the horizontal continuous casting process had not been fully developed due to the inadequacy in the technology of designing a unitary melting and casting machine and in the technology of a short term deoxidation process. Moreover, there are no relevant references for the particular details of the technology.
In order to fabricate a PCB(Printed Circuit Board) plating purpose phosphorized copper rod by means of a continuous casting process, it is necessary to develop various techniques, such as suppression of oxidation in the molten metal, deoxidation in a furnace for deoxidizing the oxygen contained therein, transferring of the molten metal from the melting furnace to the casting machine, suppression of oxidation of the molten metal during such transferring, secondary deoxidation and refining in the casting machine, production of fine microstructure through rapid cooling, cold and hot working, and the like.
Accordingly, these various techniques have had some problems in terms of productivity and simplification of the process. Furthermore, a unitary apparatus for a horizontal continuous casting machine of the conventional resistance heating type requires a long period of time for melting and holding the temperature, thus, making the prevention of inflow of oxygen difficult and the productivity low.
Moreover, the traditional method of production of large billets for an extrusion process encompasses the problems of: segregation of P, coarsening of the microstructure, decrease in productivity, increase in product cost, inability to produce a high quality PCB plating purpose phosphorized copper which requires minimal impurities, and inability to give the required physical and electrical properties.
It means that, until now, PCB plating purpose phosphorized copper is used in the form of a ball, slab, or nugget where the use of the method of production of large area billets through extrusion process resulted in the tremendous loss of energy and a costly spending for apparatus construction.
The present invention has been devised to remedy the aforementioned problems with respect to the continuous casting process of copper alloys. In order to produce oxygen-free copper or special alloys by means of using the horizontal continuous casting process, the conventional apparatus comprises a melting furnace, a casting machine, a runner connecting the melting furnace to the casting machine, a cooling system which is connected to the casting machine for solidifying the molten metal, and withdrawing rolls which pull out the cast product. However, the present invention provides a one-body melting and casting machine that is designed to utilize high frequency induction heating. More specifically, the present invention relates to the art of employing a system in which graphite flakes are applied onto the surface of the molten metal for the sake of deoxidation and refining of the molten metal. Wherein multi-staged graphite filters are installed inside the unitary melting and casting machine, and a pair of first and second bubblers which can blow in inert gas is inserted into molten metal through one of the graphite filters.
Moreover, by applying such technology as in the present invention, oxygen-free copper or special copper alloys of high quality can be manufactured with the horizontal continuous casting process by controlling the amount of oxygen or impurities. Also, the cooling system, which is designed to give a maximum cooling effect, enables the horizontal continuous casting machine to produce small diameter phosphorized copper rods with a very fine microstructure. Thus, an elimination or minimization of additional process can be achieved resulting in a simplified process of manufacturing phosphorized copper balls through cold or hot working.
This invention, by means of horizontal continuous casting process, can simplify the manufacturing process by directly producing small diameter phosphorized copper rods which are, then, cut to an appropriate length which, then again, are used to produce phosphorized copper balls or ovals that meet the required measurement as final products. As an example, in order to manufacture a phosphorized copper ball of 45 mm"PHgr", a rod of 32 mm"PHgr" and 60 mm in length of same volume is required. Accordingly, this invention can cast a rod of 32 mm"PHgr" and cut it at the length of 60 mm to yield the required material and; therefore, reducing the manufacturing cost.